It has been previously demonstrated that bacterial endotoxins or lipopolysaccharides (LPS) play an important role in the pathogenesis of rheumatoid arthritis (RA) in an in vitro model of human chondrocytes. For example, LPS physically interact with collagen type II in the extracellular matrix (ECM) and trigger cartilage inflammation and degeneration.
Flavonoids are a diverse class of compounds found in a large variety of plants and herbs that have shown some benefit on human health. For example, U.S. Patent Publication 2013/0210753 describes methods for treating muscular dystrophies using flavonoids.
Baicalin and catechin are two types of flavonoids. Baicalin and catechin together act as a dual inhibitor of cyclooxygenase (COX) and 5-lipoxygenase (LOX), down-regulating gene and protein expression of several inflammatory mediators, possessing antioxidant effects and exerting beneficial effects in both in vitro and in vivo experimental models. Baicalin and catechin are the principal active ingredients in Limbrel, a medical food marketed by Primus Pharmaceuticals, Inc., Scottsdale Ariz., for the management of metabolic processes that underlie osteoarthritis. Limbrel® is supplied as an oral capsule, and contains from 250 to 500 mg of baicalin and catechin combined, for administration once or twice daily.
Curcuminoids are a class of potent anti-inflammatory phytochemicals which modulate the activation of NF-κB by inhibiting upstream kinases. Examples include curcumin, demethoxycurcumin, and bisdemethoxycurcumin. Previously, curcumin has been demonstrated to have a protective role on IL-1β induced Cox-2, VEGF, MMP-3 and MMP-9 in chondrocytes. Curcumin has been approved as a food additive by the United States Food and Drug Administration (FDA).
The aim of this work was to investigate the effects of curcuminoids and flavonoids on articular chondrocytes in vitro, and to develop a method and formulation that can effectively modulate the metabolic processes that underlie inflammatory conditions, and thereby treat inflammation.